1. Field of the Invention
This invention relates to a slide door-carrying cab for construction machines.
2. Description of the Related Art
The known slide door-carrying cabs for construction machines include the cab for construction machines disclosed in, for example, Japanese patent publication (JP-A-2001-49696), pages 3 to 4, FIGS. 2 and 7. According to this patent publication, a turntable is provided on a traveling gear which is at a lower portion of a construction machine, and a cab in the position on the turntable which is offset from the center of a swinging movement thereof. The cab is formed so that an outer side portion thereof bulges outward curvilinearly. The outer side portion of the cab is provided with a slide door, and a radius of curvature of a rear half section of the outer side portion is set smaller than that of a front half section thereof. Consideration is given to the slide door so that an orbit of an outer edge portion of the slide door in opening and closing movements thereof stays within a turning radius of an outer edge portion of the turntable.
FIG. 3 is a perspective view of the cab disclosed in this patent publication. The construction of the cab will be described in detail on the basis of what is shown in FIG. 3. The cab 20 is provided with a front portion 21, a top plate portion 22, an inner side portion 23, a rear portion 24, and an outer side portion 25 having a slide door 30 in a front half section 27 thereof and a wall surface portion in a rear half section 26 thereof. The slide door 30 is slidingly moved with the slide door 30 guided by an intermediate guide rail 31, an upper guide rail 32 and a lower guide rail 33 which are provided on the outer side portion 25. The outer side portion 25 is formed so as to have an outwardly bulging curvilinear surface, and the radius of curvature of the rear half section 26 of the same portion 25 is set smaller than that of the front half section 27 thereof, i.e. the slide door 30. The front portion 21 is provided with front glass 21a, the inner side portion 23 flat side glass 23a, the rear portion 24 flat rear glass 24a, and the rear half section 26 of the outer side portion 25 two-dimensional curved glass 26a respectively.
This patent publication says that, when the slide door 30 is opened, the lateral size of a rear half portion of the cab 20 can be widened owing to the above-described structure to as great an extent as possible without causing a rear end portion of the slide door 30 to project to the outside of the turning radius of a swinging movement of an outer edge of the turntable, and that an effective space in the cab can thereby be enlarged limitlessly.
FIG. 4 is a side view of a rear-end small-turn type power shovel 1, an example of a construction machine on which the cab disclosed in the above patent publication is mounted. A turntable 3 swingably mounted on a traveling gear 2 is mounted with the cab 20. A front end portion of the turntable 3 is mounted on a working machine 4. According to what is shown in FIG. 7 in this patent publication, a rear portion of the cab 20 is made of a flat vertical wall.
FIG. 5 is a sectioned side view of a mode of embodiment to which an operator's seat 40 is added of the cab 20 disclosed in the above patent publication, and FIG. 6 is a plan view of the same embodiment. Referring to FIGS. 5 and 6, the cab 20 is fixed in the position on the turntable 3 which is offset from the center C of a swinging movement thereof 3, and an outer edge (a broken line shows a turning circle of the slide door 30 being opened) of a turning circle of the slide door 30 being opened and closed stays within a turning radius R of the outer edge of the turntable 3. The cab 20 is provided with a total of five support posts 34a, 34b, 34c, 34d, 34e in the four left and right corners thereof and at an intermediate section of the portion thereof which is on the side of the slide door 30. In the interior of the cab 20, an operator's seat 40 having a back 41 against which the back of an operator can be reclined is provided.
In this structure, flat vertical rear glass 24a is provided in the rear portion 24 of the cab 30, so that a clearance M between the back 41 of the operator's seat 40 and the rear glass 24a is narrow. The clearance M is really too narrow to place, for example, a tool box therein, and proves inconvenient. Moreover, in order to recline the back 41, a reclining angle β cannot be set large, and an operator therefore cannot take a break in a comfortable posture during a rest period.